// 参考 https://github.com/darknessomi/musicbox/wiki/
'use strict'
const crypto = require('crypto')
const bigInt = require('big-integer')
const modulus = '00e0b509f6259df8642dbc35662901477df22677ec152b5ff68ace615bb7b725152b3ab17a876aea8a5aa76d2e417629ec4ee341f56135fccf695280104e0312ecbda92557c93870114af6c9d05c4f7f0c3685b7a46bee255932575cce10b424d813cfe4875d3e82047b97ddef52741d546b8e289dc6935b3ece0462db0a22b8e7'
const nonce = '0CoJUm6Qyw8W8jud'
const pubKey = '010001'

String.prototype.hexEncode = function() {
	let hex, i

	let result = ''
	for (i = 0; i < this.length; i++) {
		hex = this.charCodeAt(i).toString(16)
		result += ('' + hex).slice(-4)
	}
	return result
}

function createSecretKey(size) {
	const keys = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
	let key = ''
	for (let i = 0; i < size; i++) {
		let pos = Math.random() * keys.length
		pos = Math.floor(pos)
		key = key + keys.charAt(pos)
	}
	return key
}

function aesEncrypt(text, secKey) {
	const _text = text
	const lv = new Buffer('0102030405060708', 'binary')
	const _secKey = new Buffer(secKey, 'binary')
	const cipher = crypto.createCipheriv('AES-128-CBC', _secKey, lv)
	let encrypted = cipher.update(_text, 'utf8', 'base64')
	encrypted += cipher.final('base64')
	return encrypted
}

function zfill(str, size) {
	while (str.length < size) str = '0' + str
	return str
}

function rsaEncrypt(text, pubKey, modulus) {
	const _text = text.split('').reverse().join('')
	const biText = bigInt(new Buffer(_text).toString('hex'), 16),
		biEx = bigInt(pubKey, 16),
		biMod = bigInt(modulus, 16),
		biRet = biText.modPow(biEx, biMod)
	return zfill(biRet.toString(16), 256)
}

function Encrypt(obj) {
	const text = JSON.stringify(obj)
	const secKey = createSecretKey(16)
	const encText = aesEncrypt(aesEncrypt(text, nonce), secKey)
	const encSecKey = rsaEncrypt(secKey, pubKey, modulus)
	return {
		params: encText,
		encSecKey: encSecKey
	}
}

module.exports = Encrypt
